More than likely we've all experienced the moment of panic as the most underdressed person in the room. I'd imagine most of us prefer to be overdressed rather than the opposite. When it comes to planning a wedding outfit (a favorite thing to do!) often the invitation or wedding website will mention a dress code. You may not be super close to the happy couple and not want to text or call to ask about attire just days or weeks before the wedding. What do you do when you've left the dress code to the 11th hour, there are no mentionings of dress code to be found, and you begin to panic about what to where?
First, start by researching the venue. The wedding website may not mention dress code but it likely gives a location and time. The venue can give you many clues as to expected dress when it was not mentioned on any provided information. Indoors at a luxury, boutique hotel will likely be a more black-tie or formal occasion where outdoors along the river at a popular barbeque pit will let you know to lend an air of casual formality to your outfit.
Did the venue lead you anywhere? Pull out the wedding invitation and evaluate for further details. Whether or not anything is listed, look at the quality of the invitation. Thick cardstock with personalized, flourished ink will tell you this is likely not the place to wear your cowboy boots and denim jacket. More than likely black-tie attire would be required if the invitation is high end. If the invitation is homemade and printed off of the couple's personal printer, the wedding is likely less formal.
If all of your research is leading nowhere, pull out your little black dress (navy works too). A tea length hemline is more appropriate than a short dress one for most venues. Dress up your tried and true with some statement jewelry or a boldly colored pair of shoes. Without knowing if the venue is on the grass or indoors, a wedge may be ideal to avoid sinking heels and tea length would be better than a gown to avoid tripping on the dress if you can't wear your heels.